Air quality in and around road tunnels
Roads and Maritime Services adhere to strict conditions
set down by the former NSW Department of Planning
for the maximum allowable levels of vehicle emissions in
the air both in and outside its tunnels. These standards
are recommended by the World Health Organisation and
the National Environmental Protection Council.
Air quality monitors in and outside the tunnels constantly
measure the presence of carbon monoxide, nitrogen
dioxide, fine particles and visibility levels.
External air quality in the suburbs adjacent to tunnels
will vary during the year due to seasonal climate variations,
wind speeds and external events such as dust storms,
bush fires and construction works in the area.
Air quality management
Tunnel air quality is monitored 24 hours per day.
It is managed by ventilating the tunnels with fresh air
which dilutes the pollutants emitted from vehicles as they
travel through the tunnels. How air quality is managed
in individual tunnels varies and is determined by several
· Length of tunnel.
· Volumes of traffic.
· Number and location of ventilation buildings,
jet fans, axial fans, fresh air intake points,
crossover passages and bypasses.
· Physical constraints within the tunnel.
· Operating Conditions of Approval
(as set by the former Department of Planning).
Even though traffic volumes have significantly increased
over time, Sydney’s air quality has improved and is now
cleaner than it was two decades ago with big improvements
in vehicle emissions mainly due to stricter fuel and
vehicle emission standards.
Roads and Maritime Services is committed to improving
air quality by effectively managing its road network and
traffic system and will continue to work towards reducing
vehicle emissions and supporting initiatives that help
keep our air clean.